Reverse-relay device.



NO. 816,111. PATENTED MAR. 27, 1906 R. D. MERSHON.

REVERSE RELAY DEVICE.

APPLICATION FILED 11017.4,1904.

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No. 816,111. PATENTED MAR. 27, 1906.

' R. D. MBRSHON. REVERSE RELAY DEVICE.

APPLIOATION FILED NOV/1,1904.

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PATENTED MAR. 27, 1906.

R. D. MERSHON. REVERSE RELAY DEVICE.

APPLICATION FILED NOV. 4. 1904.

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qxhmam z [9, 5440mm RALPH D. MERSHON, OF NEW YORK, N. Y.

REVERSE-RELAY DEVICE.

Specification of Letters Patent.

Patented March 27, 1906.

' Application filed November 4,1904. Serial No. 231.331.

To all whom it may concern/.-

Be it known that I, RALPH D. MERsHoN, a citizen of the United States,residing at New York, in the county and State of New York, have inventedcertain new and useful Im- .provements in Reverse-Relay Devices, of

wlnch the following is a specification, reference being had to thedrawings accompanying and forming part of the same.

My present invention relates to a class of apparatus known generally asreverse-re lays, used in connection with a system comprising two or moresources of current feeding into the same circuit for the purpose ofoperating a circuit-breaker or performing other desired functions whencertain abnormal conditions occur in the system, such as a short circuitof one of the sources of current.

Reverse-relay devices are usually made in the form of a relay operatingon the wattmeter principle, having devices for closing a local circuitwhen the abnormal conditions occur, which local circuit operates orcontrols the operation of a circuit-breaker in the main circuit. Suchdevices have been found to operate more or less satisfactorily when theabnormal conditions do not depart far from normal; but they have notproved satisfactory in the extreme conditions which may be and notinfrequently are met in practice. For example, assume two circuits orsources of current feeding into the same busbars, each circuit beingprovided with a switch and a reverserelay for opening the same operatingon the principle of the wattmeter. Upon one of the circuits beingshortcircuited near the bus-bars the wattmeterrelay would, if itoperated properly, reverse its reading and, swinging back of Zero, wouldclose its local circuit, which would in turn open the switch. As amatter of fact, however, the reverse-relay devices now ordinarily usedwill not operate as just described for either or both of two reasons:First, when a short circu t occurs the voltage at the bus-bars islowered to a greater or less degree, and the component of wattmetertorque due to voltage is therefore reduced; second, in case of shortcircuit the power factor of the current is very low, wh'ch also reducesthe wattmeter torque. The result is that in the case of a severe shortcircuit the reduction of torque from one or both of these causes is sogreat that it is not suflicient to carry the reverse-relay far enoughbeyond its Zero-point in the negative direction.

The

object of my invention is, therefore, to provide reverse-relay apparatuswhich will opcrate successfully under all conditions which may occur inpractice, no matter how severe.

In carrying out my invention I may employ for each piece of apparatus arelay device which will operate under what may be described as slightlyabnormal conditions that is, when the voltage is not greatly reducedandin connection therewith one which will not operate under the slightlyabnormal conditions, but only under severely abnormal conditions, or Imay employ a single device which will operate under all conditions. Theinstrument or instruments may be electrostatic or electromagnetic, andeither kind may be constructed to operate on the dynamometer principleor on the rotating field principle. However, for the purpose ofsimplifying the description I shall confine the same to electromagneticinstruments, describing specifically two operating on thefirst-mentioned principle and one on the latter.

The essence of my invention resides in obtaining in the instrument underabnormal conditions of low voltage and low power fac tor in the circuitin which the device is connected a torque high enough to enable it toperform the desired function. This principle may be carried out in anyone or more of a variety of ways as, for example, first, by hav ng sucha fixed phase relation between the current and the electromotive forceof the shunt-circuit as will produce as great a torque as possible underthe abnormal conditions mentioned; second, by causing the voltageeffective on the shunt element of the instrument to be increased overwhat it otherwise would be when the abnormal conditions arise; third, bycausing the current in the series coils or the effect in the instrumentdue to the main current to be increased over what it otherwise would bewhen the abnormal conditions exist, or, fourth, by changing the phaserelation of the current and electromotive force in the shunt-circuit.The first will cause the instrument to'have a greater torque than anordinary wattmeter would have under the condition of low power factor,because at that time the ampere-turns of the shunt and series fieldswill have a better phase relation for producing torque than in the caseof the ordinary wattmeter. The second will increase the torque, becausethe shunt field is strengthened. The third will increase the torque,because the series field is strengthened. The forth will also increasethe torque, for the reason that the conditions which produce the lowvoltage will be accompanied by low power factor, which in the ordinarywattmeter would mean that the shunt and series magnetizations were inthe wrong phase to produce torque, so that changing the phase relationsin the proper way to produce a rotation like that of the first-mentionedmethod would increase the torque above what it would be if the abnormalphase relation persisted. The voltage effect on the shunt element may beincreased by changing the ratio of the transformer feeding theshunt-circuit or by varying the resistance, reactance, or capacityexternal to the shunt element or by other well-understood means. Thecurrent eifect on the series element may be increased by changing theratio of the series transformer used in connection with the instrumentor by other well-understood means. These operations may be effectedautomatically by a device operating on the voltmeter principle, as thevoltage falls or when it has fallen below a certain predetermined value,or by a device which depends upon the variation of other quantities,which in case of short circuit vary characteristically. For example,this automatic action may be brought about by a device operating on theammeter principle, dependent upon the fact of a large current flowingwhen a short circuit occurs. However, for this purpose I prefer thevoltmeter device. The phase relation of the series and shunt fields maybe changed by cutting into circuit with the shunt element a resistance,reactance, or capacity as may be needed. In the case of a wattmeteroperating on the ordinary dynamometer principle, and in which,therefore, the shunt-current is as nearly as possible in step with theeleetromotive force, it is desirable when the voltage is lowered to havethe current in the shunt-circuit lag, thus bringing it more nearly instep with the lagging current taken by the short circuit. As stated,this may be done by cutting reactance into the shunt-circuit. The sameresult may be secured to a greater or less ex tent by cutting resistanceout of the shuntcircuit, thereby changing the ratio of the reactance andresistance in that circuit. In the case of a wattmeter operating on theelectromagnetic inductive principle, in which the shunt-current is madeas nearly as possible ninety degrees away from the "electromotive force,the phase relation of current and electromotive force in theshunt-circuit may be changed by cutting resistance or capacity into theshunt-circuit.

The above-mentioned methods are given merely as examples of ways forrestoring or partially restoring the torque of the watt meter to a valuehigh enough for successful operation, and the explanation has beenconfined more specifically to electromagnetic in ductive and dynamometerinstruments, for the reason that these are the types now most commonlyused; but it will be seen by those skilled in the art that analogousresults may be secured in the case of electrostatic instruments also.Likewise I have mentioned only those methods of varying the phaserelations which would probably be employed for the purpose; but othermethods might be usedas, for example, that of compounding electromotiveforces, &c. It is clear, of course, that the torque may also beincreased to the de sired value by simultaneously increasing the voltageeffective on the shunt-coil and changing the phase relation.

For a more detailed explanation of my invention reference maynow be madeto the accompanying drawings, in which are shown the preferredembodiments.

Figure 1 is a diagram illustrating a system employing two instruments,one for taking care of conditions departing but slightly from normal,the other for more severely abnormal conditions, the phase relation ofthe shunt and series coils of the latter being fixed at a value suitablefor conditions accompanied by low power factor. Fig. 2 is a diagramshowing a system in which a single instrument takes care of the abnormalconditions, the torque of the instrument being made high enough for itssuccessful operation by a device operating on the voltmeter principle.Fig. 3 is a diagram also showing a system with a single instrument forall conditions operating on the principle of the inductionwattmeter,with a device operating on the voltmeter principle to make the torque ofthe wattmeter sufficiently high under severely abnormal conditions.

Throughout the various figures, S and S indicate circuits feeding acommon circuit C. At B is shown diagrammatically a circuitbreaker, andat B a tripping-coil for operating the same. The shunt and seriestransformers for the reverse-relay apparatus are indicated by t and 25,respectively.

Referring now more particularly to Fig. 1, w is a wattmeter operating onthe dynamometer principle, in which the current in the shunt-coil s isas nearly as possible in step with the electromotive force. \Vhen thisphase relation is disturbed only to a comparatively slight degree, as bya short circuit a considerable distance from the instrument, the torqueof the wattmeter may be sufficient to carry the pointer 29 or otherdevice far enough in the negative direction to connect the contacts 0 0,thus closing the circuit of battery L, energizing the coil B, andactuating the switch B. When, however, the voltage at the wattmeter isgreatly reduced or under the other very abnormal conditions beforementioned, the torque 15 in- ITO sufficient for the desired purpose andthe circuit-breaker B is not actuated I therefore provide, in additionto the wattmeter w, a device I/V, analogous to a wattmeter, but in whichthe current in the shunt-coil s is made as nearly as possible ninetydegrees lagging behind the electromotive force, a reactance B beingincluded in the shunt-circuit for that purpose. Such an instrument willtherefore take account only of such component of the main current as isninety degrees or approximately ninety degrees away from theelectromotive force producing it. This device on account of theninety-degrees phase relation just mentioned may for convenience bedesignated as a quadrature device. \Vhen conditions are such that thesource S is supplying a lagging current to the circuit C, the deflectionof the quadrature device is positive. As long as the current neitherleads nor lags-that is to say, when the power factor is unity-thequadrature device is at zero, (indicated bythe line a 1),) or nearly so.When however, the source S is receiving a leading current, as would bethe case if a short circuit occurred beyond the instruments in thecircuit S, the reversal of the phase relation of the currents in theshunt and series coils will cause the quadrature device to show adeflection in the negative direction beyond the zero-line a I) and maycarry the pointer 10 far enough to bridge the contacts 0', therebyclosing the local circuit through battery L and actuating the switch B.By proportioning one or more of the various elements of the system, asthe reactance R, the position of the contacts 0 0 relative to thezero-line, the device, (not shown) as a spring or weight, which opposesthe deflection of the pointer or by other means, the quadratureinstrument may be made to be inert, so far as affecting the localcircuit is concerned, under conditions which cause the wattmeter w toclose the local circuit and to be deflected in the negative directionagainst the local-circuit contacts only when conditions become toosevere for the wattmeter to handle. In most instances it will be foundadvisable to make the quadrature device come into action somewhat beforethe operative limit of the wattmeter is reached, so that there could beno gap between the upper limit of the former and lower limit of theother. The. local circuit may also be provided with contacts 0 c on thepositive side of the wattmeter, so that in case of overload the extremedeflection of the pointer p in the positive direction will also closethe batterycircuit and actuate the switch B.

In Fig. 2 a single instrument W, operating on the dynamometer wattmeterprinciple, is employed to take care of all conditions. Its

arm or pointer p is at all times in electrical contact with a strip orbar m, which is in encuit with the battery L. The local circuit tion, asby short circuit in the circuit S beyond the instrument. The lattercontact is carried by a movable core 1) of a voltmeter device V, heldnormally in the coil o against the tension of a spring 12 When thevoltage in the instrument falls, the magnetic field of.

the coil 1/ is weakened and the core is drawn out by its spring,carrying the contact a nearer the shunt-coil arm p Less torque will thenbe required to bring the pointer to the negative contact. The device maybe so constructed and proportioned that the contact 0 may be broughtvery close to the zeroline, near enough for the low torque of anordinary wattmeter to swing its arm over against the contact withoutother assistance but I prefer to use also some means for increasing thetorque of the wattmeter under conditions involving low voltage or lowpower factor, or both. A number of methods for increasing the torquehave been described above, and in the present instance, Fig. 2, I employthree of themna1nely, increasing the ampere-turns in the shunt-coil andalso in the series coil and changing the phase relation between theampere-turns, thus making the instrument more positive in its actionthan it might be if the movable contact 0 alone were used. To effectthis increase in ampere-turns and change the phase relation between thesame, the voltmeterdevice may be provided with suitable commutatingdevices, as D and D. As the core 11 is drawn out of the coil the brush fmakes contact with the terminals 15 successively reducing the numberofturns of the series transformer 25. At the same time the brushf makescontact with terminals 25 successively reducing the resistance R incircuit with the shunt-coil.

In Fig. 3 is shown an induction-wattmeter, to which my invention isapplied, with a movable negative contact actuated as in the systemillustrated in Fig. 2. The disk of the instrument is indicated by (Z,carrying an arm or pointer 19. The series coil of the ordi narywattmeter is designated by s and the shunt-coil by in the circuit of thelatter being a reactance B An auxiliary shunt coil 8' is provided,connected with the transformer t through a resistance R and havingseparated contact-plates t" t in its circuit. As the core 1) of thevoltmeter device is drawn up the brush f makes contact with the platesit" thus closing the circuit of the aux.- iliary shunt-coil. In theparticular arrangement shown the electromotive force im-v pressed uponthe auxiliary shunt-circuit is higher than is at the same instantimpressed upon the permanent shunt-circuit. The

auxiliary coil takes account of quadrature IIO current, and its torqueassists that of the other coil. Any number of auxiliary coils may beused, as desired, and may be brought into operation successively orsimultaneously by the voltmeter device.

The devices shown in Fig. 3 may be readily applied to existing types ofwattmeters operating on the rotating field principle.

The advantages incident to the use of a movable or adjustable contact asemployed, for example, in Figs. 2 and 3 are of particular value, as willbe readily seen. For in stance, the moving contact makes the apparatusautomatically self-adjusting, so that it may be made to perform itscircuitcontrol ling functions only and always under condi tions whichdepart a predetermined amount from normal. Thus abnormal conditions mayarise which might give considerable deflection of the instrument towardthe contact but unless the voltage dropped a certain amount (or thecurrent increased a certain amount, if the movement of the contact iseffected by an ammeter device) it would not be desirable to break thecircuit S. In that case the drop in voltage (or increase in current)would not cause the contact to be moved far enough for the arm orpointer to meet it, and the circuit S would therefore not be disturbed.

The local circuit of the switch B is shown in all the figures asnormally open; but the switch may of course be constructed so as to beopened by breaking a normally closed circuit, the two methods beingsubstantial equivalents.

It will be noted that in indicating or circuit-controlling devices suchas are herein described the torque is due to two elements, one of themdependent upon the current in the circuit which includes the device andthe other dependent upon the voltage in this circuit. The magnitude ofthe torque depends upon the respective values of the two elev ments andupon the value of the phase angle between them. The magnitude of thetorque may therefore be varied by varying one or more of these values,which may be effected in a variety of ways, as before explained. In theapparatus shown in the three figures the two elements mentioned are ineach case currents or the fields due to them, dependent in value uponthe voltage and current of the circuit in which the indicating orcircuit controlling device is connected. In the case of the instrumentsshown in Figs. 2 and 3 the torque may be varied by varying the values ofthe currents and of the phase angle between them.

Throughout the claims I have referred only to a circuitcontrollingdevice, as circuit control is in some respects the chief object of theinvention; but a mere indication of the conditions in the circuit may beall that is desired, in which case the device need not actually causethe circuit to be broken or controlled in any way. I therefore am notlimited to a circuit-controlling device properly so called, but may useas well merely a device which gives an indication of the conditionspresent.

What I claim is l. The combination with a source of current connectedwith one or more other sources of current, of a circuit-controllingdevice actuated by force proportional to the vectorial product ofcomponents dependent upon current and eleetromotive force respectively,and adapted with reference to the phase relation of the said componentsto producehigher torque under conditions accompanied by low power factorthan when accompanied by high power factor, as set forth.

2. The combination with a source of current connected with one or moreothersources of current, of a circuit-controlling device actuated byforce proportional to the vectorial product of components dependent uponcurrent and eleetromotive force respectively, and means for adjustingthe magnitude and phase relation of the said components, as set forth.

3. The combination with a source of current connected with one or moreother sources of current, of a circuit-controlling device actuated byforce proportional to the vectorial product of components dependent uponcurrent and eleetromotive force respectively, and means for adjustingthe magnitude of one or more of the said components, as set forth.

4. The combination with a source of current connectedwith one or moreother sources of current, of a circuit-controlling device actuated byforce proportional to the vectorial product of components dependent uponcur rent and eleetromotive force respectively, and automatic means foradjusting the magnitude and phase relation of the said compo nents, asset forth.

5. The combination with a source of current connected with one or moreothersources of current, of a circuit-controllin device actuated byforce proportional to the vectorial product of components dependent uponcurrent and eleetromotive force respectively, and automatic means foradjusting the magnitude of one or more of the said components, as setforth.

6. The combination with a source of current connected with one or moreother sources of current, of a circuitcontrolling device actuated byforce proportional to the vectorial product of components dependent oncurrent and eleetromotive force respectively, and automatic means foradjusting the magnitude and phase relation of the said components,dependent for operation upon decrease of voltage, as set forth.

7. The combination with a source of cur- IIC rent connected with one ormore other sources of current, of a circuit-controlling device actuatcdby force proportional to the vectorial product of components dependentupon current and electromotive force respectively, and automatic meansfor adjusting the magnitude of one or more of the said components,dependent for operation on decrease of voltage, as set forth.

8. The combination with. a source of current connected with one or moreother sources of current, of a circuit-controlling device connected withthe first-mentioned source, a local circuit, a movable contact therein,a circuit-closing device actuated by the circuitcontrolling device, andmeans for moving the contact toward the circuit-closing device, theoperation of said means being dependent upon, and proportional in extentto, abnormal electrical conditions in the external circuit of thecircuit-controlling device, as set forth.

9. The combination with a source of current connected with one or moreother-sources of current, of a circuit-controlling device connected withthe first-mentioned source, a local circuit, a movable contact therein,a circuit-closing device actuated by the circuitcontrolling device, andmeans for carrying the movable contact toward the circuit-closingdevice, the operation of the said means being dependent upon, andproportional in extent to, decrease of voltage in the external circuitof the circuit-controlling device, as set forth.

10. The combination with a source of current connected with one or moreother sources of current, of a circuit-controlling device connected withthe first-mentioned source and actuated by force proportional to thevectorial product of components dependent upon ,urrent and electromotiveforce, a local circuit, a movable contact therein, a circuitclosingdevice, actuated. by the circuit-controlling device, means for movingthe contact toward the circuit-closing device, means for adjusting themagnitude andv phase relation of the said components, and mechanism foractuating both said means, dependent for op eration upon abnormalconditions in the external circuit of the circuitcontrol-ling device, asset forth.

11. The combination with a source of current connected with one or moreother sources of current, of a circuit-controlling device connected withthe first-mentioned source and actuated by force proportional to thevectorial product of components dependent upon current and electromotiveforce, a local circuit, a movable contact therein, a circuitclosingdevice actuated by the circuit-com trolling device, means for moving thecontact toward the circuit-closing device, means for adjusting themagnitude of one or more of the said components, and mechanism foractuating both said means, dependent for oper ation upon abnormalelectrical conditions in the external circuit of thecircuit-controllingdevice, as set forth.

12. The combination with a source of current connected with one or moreother sources of current, of a circuit-controlling device con nectedwith the first-mentioned. source and actuated by force proportional tothe vectorial product of components dependent upon current andelectromotive force, a local circuit, a movable contact therein, acircuitclosing device, actuated by the circuit-controlling device, meansfor moving the contact toward. the circuit-closing device, means foradjusting the magnitude and phase relation of the said components, andmechanism for actuating both said means, the operation of said mechanismbeing dependent upon, and proportional in extent to, decrease of voltagein the external circuit of the circuit-controlling device, as set forth.

13. The combination with a source of current connected with one or moreother sources of current, of a circuit-controlling device connected withthe first-mentioned source and actuated by force proportional to thevectorial product of components dependent upon current and electromotiveforce, a local circuit, a movable contact therein, a circuitclosingdevice, actuated by the circuit-controlling device, means for moving thecontact toward the circuit-closing device, means for adjusting themagnitude of one or more of the said components, and mechanism foractuating both said means, the operation of said mechanism beingdependent upon, and proportional in extent to, decrease of voltage inthe external circuit of the circuit-controlling device, as set forth.

RALPH D. MERSHON.

